@article{54966,
  abstract     = {{Piezoresponse force microscopy (PFM) is one of the most widespread methods for investigating and visualizing ferroelectric domain structures down to the nanometer length scale. PFM makes use of the direct coupling of the piezoelectric response to the crystal lattice, and hence, it is most often applied to spatially map the three-dimensional (3D) near-surface domain distribution of any polar or ferroic sample. Nonetheless, since most samples investigated by PFM are at least semiconducting or fully insulating, the electric ac field emerging from the conductive scanning force microscopy (SFM) tip penetrates the sample and, hence, may also couple to polar features that are deeply buried into the bulk of the sample under investigation. Thus, in the work presented here, we experimentally and theoretically explore the contrast and depth resolution capabilities of PFM, by analyzing the dependence of several key parameters. These key parameters include the depth of the buried feature, i.e., here a domain wall (DW), as well as PFM-relevant technical parameters such as the tip radius, the PFM drive voltage and frequency, and the signal-to-noise ratio. The theoretical predictions are experimentally verified using x-cut periodically poled lithium niobate single crystals that are specially prepared into wedge-shaped samples, in order to allow the buried feature, here the DW, to be “positioned” at any depth into the bulk. This inspection essentially contributes to the fundamental understanding in PFM contrast analysis and to the reconstruction of 3D domain structures down to a 1 μm-penetration depth into the sample.}},
  author       = {{Roeper, Matthias and Seddon, Samuel D. and Amber, Zeeshan H. and Rüsing, Michael and Eng, Lukas M.}},
  issn         = {{0021-8979}},
  journal      = {{Journal of Applied Physics}},
  keywords     = {{Ferroelectrics, lithium niobate, piezoresponse force microscopy}},
  number       = {{22}},
  publisher    = {{AIP Publishing}},
  title        = {{{Depth resolution in piezoresponse force microscopy}}},
  doi          = {{10.1063/5.0206784}},
  volume       = {{135}},
  year         = {{2024}},
}

@article{9744,
  abstract     = {{Direct ultrasound irradiation is advantageous to increase the efficiency of the hydrothermal method which can be used for the production of piezoelectric thin films and lead free piezoelectric ceramics. To apply ultrasound directly to the process transducer prototypes were developed regarding the boundary conditions of the hydrothermal method. LiNbO$_{3}$ and PIC 181 were proven as feasible materials for high temperature resistant transducers ($\geq 200^\circ C$). Resistance of the transducers horn against the corrosive mineralizer was achieved by using Hastelloy C-22. The efficiency of the ultrasound assisted hydrothermal method depends on the generated sound field. Impedance and sound field measurements have shown that the sound field depends on the filling level and the position and design of the transducer.}},
  author       = {{Bornmann, Peter and Hemsel, Tobias and Littmann, Walter and Ageba, Ryo and Kadota, Yoishi and Morita, Takeshi}},
  issn         = {{1948-5719}},
  journal      = {{Journal of Korean Physical Society}},
  keywords     = {{High-temperature transducer, Hydrothermal method, Lithium-niobate transducer}},
  number       = {{4}},
  pages        = {{1122}},
  title        = {{{Ultrasonic Transducer for the Hydrothermal Method}}},
  doi          = {{10.3938/jkps.57.1122}},
  volume       = {{57}},
  year         = {{2010}},
}